“No Java compiler was found to compile the generated source for the JSP. ” 应该是环境变量没有配置好吧?好像是找不到编译的相关工具。(org.apache.jasper.JasperException: Unable to compile class for JSP)
仔细看这一句错误提示: This can usually be solved by copying manually $JAVA_HOME/lib/tools.jar from the JDK to the common/lib directory of the Tomcat server, followed by a Tomcat restart. 这个能经常被解决通过手工地拷贝$JAVA_HOME/lib/tools.jar 到tomcat的common/lib ,紧跟着一个tomcat的重新启动。
This can usually be solved by copying manually $JAVA_HOME/lib/tools.jar from the JDK to the common/lib directory of the Tomcat server, followed by a Tomcat restart. 这个能经常被解决通过手工地拷贝$JAVA_HOME/lib/tools.jar 到tomcat的common/lib ,紧跟着一个tomcat的重新启动。
<html>
<head>
<title>JSP连接MySQL!</title>
</head>
<body>
<%@ page language="java" import="java.sql.*" %>
<jsp:useBean id="DBconn1" scope="page" class="mysqltest.DBconn" />
<%
ResultSet RS = DBconn1.executeQuery("SELECT * FROM userdata");
while (RS.next()) {
out.print("<h1>" + RS.getString("username")
+"</h1>");
}
RS.close();
%>
</body >
</html >你的多了一个花括号。如果不是这里的问题,你再检查一下jdbc驱动程序是否放置到了tomcat5.0.12的安装目录/common/lib目录下。再解决不了,就请bill来解决吧!他的办法问题少。
应该是环境变量没有配置好吧?好像是找不到编译的相关工具。(org.apache.jasper.JasperException: Unable to compile class for JSP)
如果不符合jsp写法,会报这样的错误
// }
2.配置环境变量
我的电脑->属性->高级->环境变量->系统变量
增加JAVA-HOME = c:\jdk1.4.2 或其它实际安装的路径
后修改PATH = %JAVA_HOME%\bin;.;%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\lib\tools.jar
This can usually be solved by copying manually $JAVA_HOME/lib/tools.jar from the JDK
to the common/lib directory of the Tomcat server, followed by a Tomcat restart.
这个能经常被解决通过手工地拷贝$JAVA_HOME/lib/tools.jar 到tomcat的common/lib ,紧跟着一个tomcat的重新启动。
<%@ page contentType="text/html; charset=gb2312" %>
<html>
<head>
<title>JSP连接MySQL!</title>
</head>
<body>
<%@ page language="java" import="java.sql.*" %>
<jsp:useBean id="DBconn1" scope="page" class="mysqltest.DBconn" />
<%
ResultSet RS = DBconn1.executeQuery("SELECT * FROM test");
while (RS.next()) {
out.print("<h1>" + RS.getString("col1")
+"</h1>");
}
RS.close();
}____________此处多了一个括号
%>
</body >
</html >
to the common/lib directory of the Tomcat server, followed by a Tomcat restart.
这个能经常被解决通过手工地拷贝$JAVA_HOME/lib/tools.jar 到tomcat的common/lib ,紧跟着一个tomcat的重新启动。
exception org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:358)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
root cause java.lang.NullPointerException
org.apache.jsp.mysqltest_jsp._jspService(mysqltest_jsp.java:67)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
, funcreal(new PLMM[Integer.MAX_VALUE]) , tom2005(快乐着) ,jialin_2004(老猫) , huhuanaiqing(呼唤爱情) , denghan(很久没来ASP版了) , studyday(好好学习天天向上) ,谢谢你们大清早热心的帮助,现在java.lang.NullPointerException是否是null引用?问题是在DBconn.java里还是在mysqltest.jsp里,怎么来定位这个问题呢?不好意思,我接触jsp时间不长
这样你用过吗
应该是
String ConnStr="jdbc:mysql://localhost:3306/test?user=root&password=test&useUnicode=true&characterEncoding=8859_1";